| Bone defect is quite common in clinical work. How to repair the bone defect is very important in Maxillofacial Surgery, Periodontics and Prosthodontics. Currently doctors often use autogenous bone graft to repair bone defect. Autogenous bone graft is good support material without immune rejection, but patients will suffer more because of the second surgical region. So we want to make new tissue-egineering material repair bone defect alternativing autogenous bone graft .The experiment was divided into two parts: first, the preparation and synthesis of composite materials and related test; Second, it take animal experiments to observe the effect of composite repairing bone defects.The preparation and synthesis of composite materials1 Recombinant human lactoferrin were loaded into chitosan microspheres by emulsion crosslinking method And it's release reasult were evaluated invitro. In this study, chitosan microspheres loaded with lactoferrin were generally observed as pale yellow powder. under electron microscope, the chitosan microspheres showing uniformly spherical and good form microspheres, Diameter = 30-50μm. The surface was porous without folds and no significant adhesion was between microspheres. The loading rate and entrapment efficiency of the complex was 1.06±0.06% and 88.2±2.9%.2 Nanosized hydroxyapatite was prepared through Chemical precipitation and treated at 800℃.The samples of Nanosized hydroxyapatite were observed as granular and regular shape with diameter 70-90nm in line with nano-level requirements.3 Collagen I was extracted from fresh bovine tendon by acid dissolution and protease digestion. The freeze-dried collagen was pale yellow, flocculent, porous, soft and elastic texture. Under scanning electron microscope, the collagen fiber arranged in an orderly form with good morphology. 4 Co and nHA were combined into a scaffold as the experimental control. Lactoferrin loaded chitosan microspheres, nHA and Co were cross-linked by genipin in proportion and freeze-dried at low temperature (0℃). Composite materials was yellow, flocculent and porous at 4℃while pale blue at room temperature. The composite microstructure of composite materials cross-linked by genipin was uniform and three-dimensional porous network structure. with porosity of 92%.Aniamal experimentsThe subjects(rabbits) were divided into experimental group, control group1, control group2 and control group, which were implanted with different materials into skull defects. Animals were sacrificed accordingly at 4 , 8 and 12 week. The average relative density of bone defect was measured by X-ray and Digora digital imaging system. The results showed that experimental group was better than the other groups in repairing bone defects. HE results suggested that the varying degrees reparing activity were at all time without immune rejection and the composite materials were completely absorbed.at8 week.The results showed that chitosan microspheres are excellent carrier of lactoferrin and help it release slowly. Lactoferrin can be used as cell growth factor into the field of tissue engineering and repair bone defects because of its antibacterial, anti-inflammatory effect and promoting bone repairing. Genipin can be effectively crosslinked chitosan microspheres, nHA and collagen together to form an organc to induce and guide bone.Therefore, lactoferrin-loaded chitosan microspheres / nHA / Co composite scaffold is a new bioactive bone substitute and support materials for bone tissue engineering. |
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